Cathode-ray tube



Feb. 1,1949. a SZEGHO 2,460,608

CATHODE-RAY TUBE Filed Jan. 12, 1945 25 ATTORNEY Patented Feb. 1, 1949 Constantin S. Szegho, Chicago, Ill., assignorgto The Rauland Corporation, Chicago, 111., a corporation of Illinois Application January 12, 1945, Serial No. 572,456

14 Claims.

This invention relates to new and useful improvements in cathode ray tubes and its object is to reduce their dimensions without endangering the strength of the glass structure.

According to the present invention, this object is accomplished by providing the electron gun, focusing means, and preferably also the deflecting means of the tube, partly at least, within a reentrant part of the main chamber or bulb portion of the tube.

This and other features of the invention will more clearly appear from the following description of an embodiment thereof and the appended claims.

The drawings illustrate side elevations of as much of a cathode ray tube as is necessary to explain the invention, Figs. 1 and 2 illustrating the general state of the art, and Figs. 3, 4 and 5 three embodiments of my improved tube.

Fig. 1 illustrates the proportions of a conventional twelve-inch cathode ray tube whose main chamber or bulb is designated by I. The tube is provided with the usual fluorescent screen 2 on the inside surface of the face 3. The tube also has a neck or sleeve portion 4 within which is located electron gun 5 and which is surrounded by focusing means, e. g. coil 6, and deflection means, e. g. magnets 1. V

If one reduced the overall length of the'tube shown in Fig. 1 to one-half and still maintained the ratio of distance from the cathode 5 to the center of the focusing coil 6, and from the latter to the screen 2, i, e., the ratio between distances at and b, then the configuration of the tube would be somewhat like the one illustrated in Fig, 2,

Obviously, the radius of curvature of the bend 8 near the face 3 of the bulb of Fig. 2 is smaller than that of bulb l in Fig. 1, whereby the bulb of Fig. 2 will be relatively weak.

According to the present invention, the cathode, and the focusing and deflecting means are mounted within a reentrant part of the bulb. As shown in Fig. 3, I!) is the bulb or main chamber which carries on its face ll formed of one piece therewith, the customary fluorescent screen I 2. The bulb I0 is provided, centrally with respect to screen I2, with a reentrant neck l3 to which is attached a hollow sleeve [4 or auxiliary chamber of substantially the same length as neck 4 in Fig. 1. The reentr-ant portion I 3, after entering the space of the main chamber Ill, returns to its point being equal to of entrance forming an air space between the defined in the claims.

of one piece of glass and have concentric cylindrical shapes of approximately the same linear extensions. In the end of sleeve I4 is sealed the means for customary producing the electron beam, the electron gun I 5. A focusing coil l6 and deflection coils ll are mounted around the sleeve I 4 within said air space afforded by the reentrant neck 13.

The radius of curvature of the bend 'corresponding to 8 will be at least as great as, and normally greater than, that of the bulbs of Figs. 1 and 2.

The sleeve 14 should be of smaller diameter than sleeve 4 of Fig. 1 to accommodate the defleeting and focusing coils and also to increase the deflection power of the coils. To avoid shadowing of the deflected beam, the sleeve l4 should have an elliptical cross section.

It will be seen, therefore, that the outline of the main chamber or bulb I0 is geometrically generated substantially by the rotation of a line of continuous curvature about the axis of electron producing means l5 and the auxiliary chamber M. The line of curvature is convex towards and starts close to the axis of i5, and gradually moves away from it. The axis of i5 is perpendicular to screen [2 which covers the opening formed by the outline of In.

In addition to the obvious advantages arising from the shortness of the tube, i. e., greater security and less space required in handling and mounting the tubes, an added advantage of the novel construction is that reflections by the side wall of the bulb ill will not fall on the screen 2. As indicated by dotted lines l8 and I9 in Figs. 1

' and 2, at least some of the reflections from the side wall of the bulb reach the fluorescent screen. Owing to the fact that the side Wall of bulb i0 is not inclined as sharply as in the bulbs shown in Figs. 1. and 2, no reflection from the side wall can reach the screen I2.

Obviously, modifications in the construction and assembly of the elements of the tube may be effected without departing from the invention as For instance, instead of electromagnetic deflecting means ll electrostatic means may be provided in auxiliary chamber M. Or, as' shown in Fig. 4, a socket 26 on the end of returning part of a reentrant portion of a glass envelope may be provided with pins 2| to connect the cathode or any other electrodes with outside circuits. The socket 20 may alsoserve to support electromagnetic focusing and deflecting systems on a structure space formed between portions of the tube. The assembly of the tube 7 elements and of the finished tube itself is facilitated,

Another of the many possible modifications is shown in Fig. in which the face 23 carrying the screen of a cathode ray tube 24 is fiat and rectangular, instead of circular and curved as in Fig. 3, and the side walls truncated. While this glass bulb structure has certain disadvantages over the others here shown and claimed, it may be preferred by some on account of the shape of its screen.

What I claim is:

1. In a cathode ray tube, an envelope having a main chamber with a reentrant portion, a, fluorescent screen within said main chamber, said envelope having also an auxiliary chamber within the reentrant portion, means for producing an electron beam within said auxiliary chamber, and means enclosing within said reentrant portion for deflecting said electron beam.

2. In a cathode ray tube, an envelope having a main chamber with a reentrant portion, a fluorescent screen within said main chamber, said envelope having also an auxiliary chamber within the reentrant portion, means for producing an electron beam within said auxiliary chamber, and means enclosed within said reentrant portion for focusing said electron beam.

3. In a cathode ray tube, an envelope having a main chamber with a reentrant portion, a fluorescent screen within said main chamber, said envelope having also an auxiliary chamber within the reentrant portion, means for producing an electron beam within said auxiliary chamber, and electrostatic means enclosed within said reentrant portion for deflecting said electron beam.

4. In a cathode ray tube, an envelope having a reentrant portion enclosing means for producing an electron beam and electromagnetic means for deflecting said electron beam.

5. In a cathode ray tube, an envelope having a reentrant portion enclosing means for producing an electron beam, electromagnetic means for focusing the beam, and electromagnetic means for deflecting the beam.

6. In a cathode ray tube an envelope having a:

a main chamber with a reentrant portion, a fluorescent screen within said main chamber, said envelope having also an auxiliary chamber within the reentrant portion, means for producing an electron beam within said auxiliary chamber,.

said reentrant portion extending into the main chamber to a predetermined point at which point it is reentrant upon itself and extends toward its point of entrance forming an air space surrounding the auxiliary chamber, and electro:

magnetic means for controlling the beam supported within said air space.

7. In a cathode ray tube as in claim 6, and in which said reentrant portion comprises an outer cylindrical tube which is reentrant into the main chamber to said predetermined point and an innercylindrical tube which is reentrant from said predetermined point into the outer tube extending toward the point of entrance thereto into the main chamber and being concentric thereof.

8. A cathode ray tube having an envelope c0mprising an externally bulb-shaped main portion and a reentrant portion surrounded by the main portion and enclosing electron producing and.

electron directing means, the envelope having an outline geometrically generated substantially by the rotation of a line of continuous curvature, said rotation being effected about the axis of said electron producing means, said line crossing said axis at. angles of about ninety degrees at two points where the axis passes through opposite sides of the envelope and being convex toward said axis.

9. A cathode ray tube according to claim 8 wherein the reentrant portion comprises an outer tube which is reentrant into the bulb-shaped main portion in a first direction along said axis and an inner tube which is reentrant into the outer tube and extends therethrough in a direction opposite to said first direction, and substantiallyall of the reentrant portion is enclosed within said outline.

10. A cathode ray tube according to claim 8 wherein the reentrant portion comprises an outer tube which is reentrant into the bulb-shaped main portion in a first direction along said'axis and an inner tube which is reentrant into the outer tube and extends therethrough in a direction opposite to said flrstdirection, and the tube comprises a socket attached to the envelope near the point of entrance of the outer tube.

11. A cathode ray tube having an envelope enclosing electron producing and. electron directing means and having an outline geometrically generated substantially by the rotation of a line of continuous curvature, said rotation being effected about the axis of said electron producin having a reentrant portion enclosed within said outline, the reentrant portion comprising an outer tube which is directly reentrant into an envelope and an inner tube which is reentrant back into the outer tube-and extends through it toward its point of entrance into the envelope, the outerand inner tubes enclosing between them a cylindrical airspace, a socket attached to the envelope near to said point of entrance, and said electron directing means comprising electromagnetic focusing and deflecting means supported by said socket in said air space.

12. In a cathode ray tube an envelope having a bulb portion enclosing a main chamber and a reentrant portion which extends into the main chamber and at least'partly encloses an auxiliary chamber, means Within the auxiliary chamber for producing a beam of electrons and electromagnetic beam focusing means supported within the reentrant portion outside of the auxiliary chamber.

13. In a cathode ray tube an'envelope having a bulb portion enclosing a main chamber and a reentrant portion which extends into the main chamber and at least partly encloses an auxiliary chamber, means within the auxiliary chamber for producing a beam of electrons, and electromagnetic beam deflecting means supported within the reentrant portion outside of the auxiliary chamber.

14. In a cathode ray tube an envelope having a bulb portion enclosing a main chamber and a reentrant portion which extends into the main chamber and at least partly encloses an auxiliary chamber, the bulb portion of the envelope comprising side wall structure, facing the auxiliary chamber, a relatively flat window wall for permitting fluorescent'light to pass out of the tube, the angle at which any part of the side wall extends toward its juncture with the window-wall being nearly ninety degrees for preventing excessive strain on the juncture due to forces exerted by external air pressure on the side wall structure and the window wall which tend to push them toward each other.

CONSTANTIN S. SZEGHO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,899,568 Hofman Feb. 28, 1933 1,953,470 Ehrke et a1. Apr. 3, 1934 Number Number 

